The intention of this conference to explore the issue of the appropriate study design for assessing the efficacy of screening for lung cancer, notably CT screening, the various methodologic issues and the their relative merits and limitations of the different designs. We plan to bring together a group of experts in study design (epidemiologists and statisticians), lung cancer experts with direct clinical involvement in lung cancer treatment, radiologists, pulmonologists, and pathologists. While the statisticians and epidemiologists will address issues of study design, the clinical experts are needed to address the ethical considerations and enrollment, radiologists will address the imaging diagnostic issues and the pathologists are needed to address the cytologic and histologic definitions of lung cancer and issues of "overdiagnosis" of lung cancer. It is planned that representatives from the NCI, ACS, ACR, UICC, and WHO will also be in attendance. Both general meetings and workshops for particular issues are planned. It has been pointed out that randomized clinical trials (RCTs) for diagnostic studies are different than RCT's for therapeutic intervention. It may indeed be true that other study designs may be more appropriate for assessment of diagnostic tests. The advantages and disadvantages of different designs should be considered including the study cost and timeliness of the results. In assessment of RCTs, there is significant opportunity in light of today's imaging tests to decide at what point the randomization should occur. Does it necessarily need to be done at the time of enrollment or could it be done once nodules are discovered, or even later when early malignancies are suspected. Each of these approaches has advantages and disadvantages in terms of efficiency as well as ethical considerations.